I have tried SXTsq 5 ac-US firmware 6.42.9 connected to an hap ac lite firmware 6.40.9 in channel 5180,5200,5745,5750 for an hour with no disconnections.I used protocols nv2,nstreme,802.11 20/40Mhz Ce.
Remember using password in nv2 protocol.Best regards from Perú.
https://ibb.co/nqOrBV